Romney, the former GOP presidential nominee who lost the 2012 election to former President Barack Obama, was also slammed by Trump for his commentary.

In a New Year’s Day op-ed for the Washington Post, Romney wrote, “It is well known that Donald Trump was not my choice for the Republican presidential nomination. After he became the nominee, I hoped his campaign would refrain from resentment and name-calling. It did not.”

Romney added, “When [Trump] won the election, I hoped he would rise to the occasion. But, on balance, his conduct over the past two years, particularly his actions last month, is evidence that the president has not risen to the mantle of the office … With the nation so divided, resentful, and angry, presidential leadership in qualities of character is indispensable. And it is in this province where the incumbent’s shortfall has been most glaring.”

The op-ed soared across social media on Tuesday evening, and was still the talk of the town on Wednesday morning.

Though Romney would not be the first GOP senator to take a stand against Trump, he’s far more of a household name and his words are more likely to gain attention. He’s also widely respected among establishment Republicans and could wield significant influence in the Senate.

The ‘new Jeff Flake’?

Many have suggested Romney’s condemnation of Trump is a sign he’ll be the “new Jeff Flake.” In other words, they feel the incoming Utah senator will often speak out against Trump’s demeanor but still vote in line with the president the majority of the time.

Flake, who’s retiring, often frustrated many on the political left over his tendency to verbally rebuke Trump while continuing to support the president’s policies.

Along these lines, Democratic Rep. Ted Lieu on Tuesday tweeted, “Very pleased GOP Senator-elect Mitt Romney is speaking some truth about @realDonaldTrump. I just hope he isn’t another Jeff Flake who says one thing and votes the other way.”

The president tweeted, “Here we go with Mitt Romney, but so fast! Question will be, is he a Flake? I hope not. Would much prefer that Mitt focus on Border Security and so many other things where he can be helpful. I won big, and he didn’t. He should be happy for all Republicans. Be a TEAM player & WIN!”

Relatedly, Flake shared Romney’s op-ed in a tweet and referred to it as a “thoughtful piece.” In a separate tweet written in response to Trump, Flake added, “Ultimately, we’re on the same team. There are good people on both sides of the aisle.”

Trump’s GOP allies are not happy with Romney

Meanwhile, Trump’s GOP allies have gone after Romney for not standing by the president – including Republican National Committee chairwoman Ronna McDaniel.

McDaniel, who also happens to be Romney’s niece, tweeted, “POTUS is attacked and obstructed by the MSM media and Democrats 24/7. For an incoming Republican freshman senator to attack @realdonaldtrump as their first act feeds into what the Democrats and media want and is disappointing and unproductive.”

Republican Sen. Lindsey Graham, who has a close relationship with Trump, also expressed dismay at Romney’s rebuke of the president. Graham warned Romney that people praising him for going after the president will soon turn on him over his voting record.

During an interview with Fox Radio, the South Carolina senator said, “This is not the way I would have hoped things would have gotten started because I know Mitt Romney very well … I don’t know what led to this … The people who are applauding Romney today for standing up to Trump and going after Trump will turn on Romney the moment he votes for something that they don’t like.”

Graham added, “What I want Senator Romney to know it’s not just about Trump, it’s about us. Remember what they tried to do to you Mitt. When they got through with you, you were a bad guy.”

In his op-ed, Romney signaled that he will likely vote along party lines and that he’s agreed with many of Trump’s policies, but suggested he will also continue to speak out against the president when compelled to.

“I will support policies that I believe are in the best interest of the country and my state, and oppose those that are not,” Romney said. “I do not intend to comment on every tweet or fault. But I will speak out against significant statements or actions that are divisive, racist, sexist, anti-immigrant, dishonest or destructive to democratic institutions.”